L-Tyrosine

Tyrosine is not considered an essential amino acid. It is a precursor to thyroid, adrenocortical hormones, and dopamine. Some of the symptoms of its deficiency include low body temperature, low blood pressure, and restless legs. Tyrosine derives from phenylalanine.

Therapeutically, tyrosine has been used to enhance its derivatives (DOPA, dopamine, norepinephrine, and epinephrine). It is also used to alter brain activity. Brain tyrosine levels are raised by ingestion of pure tyrosine, with a high carbohydrate meal to lower levels of competing amino acids. A high-protein meal will increase blood and brain tyrosine to a degree, but not enough to affect neurotransmitter synthesis significantly.

Tyrosine is reported to help some people with Parkinson’s disease and to aid in relieving depression. It is most effective when there is a deficiency. There is evidence that small doses of tyrosine are more effective for increasing brain levels of neurotransmitters than large dosages. Although blood and brain levels of tyrosine increase with large doses, there appears to be an inhibition of the enzyme tyrosine hydroxylase, which converts tyrosine to neurotransmitters when large amounts of tyrosine are present.

Tyrosine is not compatible with the intake of MAO drugs (monoamine oxidase).